This invention relates to a single-phase alternating current induction motor.
Single-phase induction motors have customarily been designed and utilized for fractional horsepower applications and have generally been classified in accordance with the methods of starting. Certain types of single-phase induction motors thus include split-phase motors, capacitor-start induction-run motors, permanent-split-capacitor motors, two-value-capacitor motors and shaded-pole motors.
Various winding methods have been employed with the single-phase induction motors to provide a desired starting torque while permitting an efficient operation at a desired rated running speed. Some motors of the shaded-pole variety utilize a salient pole stator which employs a short-circuited shading coil upon each pole portion which is directly energized by the field provided by the main winding to provide a starting torque.
Split-phase motors have employed a main or running winding and an auxiliary or starting winding which are displaced in quadrature by an angle of approximately 90 electrical degrees and are parallel connected to the single-phase power input. Such parallel connected auxiliary windings within some split-phase motors have been retained in the circuit until the rotor speed increases to approximately 75 percent of the synchronous or full running speed at which time a centrifugally operated switch disconnects the auxiliary winding so that the efficiency of the induction motor will not be effected by the presence of the auxiliary winding during a full running operation. One known split-phase motor operatively disconnects the auxiliary winding with a transformer operated switch which has a primary transformer winding serially connected to the main winding, such as shown in the Weber U.S. Pat. No. 1,433,765 issued on Oct. 31, 1922.
Various capacitor interconnections have also been employed in conjunction with auxiliary windings in order to provide a time phase displacement between the currents flowing in the main and auxiliary windings for providing a starting torque.